Tubular lining material and a method and apparatus for manufacturing same

ABSTRACT

A tubular lining material and a method and apparatus for manufacturing same, the tubular lining material being suitable for reinforcing pipe lines and comprising a tubular textile jacket having on the external surface thereof a coating of plural synthetic resins in the form of laminated layers, characterized in that the outermost layer of the coating is composed exclusively or predominantly of a thermoplastic polyester elastic resin and the innermost layer of the coating is composed exclusively or predominantly of a thermoplastic polyurethane elastic resin, the coating having been bonded superficially onto the external surface of the tubular textile jacket. The tubular lining material is manufactured by simultaneously extruding plural synthetic resins in an annularly layered form superficially onto the external surface of the tubular textile jacket, using an apparatus provided with an annularly arranged multiple extruders. The tubular lining material is significantly improved in flexibility and adhesion to the tubular textile jacket.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a tubular lining material for pipelines which comprises a tubular textile jacket overlaid superficially onthe external surface thereof with air-impervious plural coatings offlexible synthetic resins having strongly been bonded to the textilejacket and to a method and apparatus for manufacturing same. Moreparticularly, the present invention relates to a tubular lining materialfor pipe lines, especially underground pipe lines already constructed,which comprises a tubular textile jacket made of warps and a weftknitted or woven in a tubular form superficially overlaid withair-impervious plural coatings of flexible synthetic resins havingstrongly been bonded to the textile jacket and to a method and apparatusfor manufacturing same wherein a combination of synthetic resins issuitably selected and a specific device is made for simultaneousextrusion and bonding of plural synthetic resins superficially butstrong onto the external surface of the tubular textile jacket.

2. Description of the Prior Art

In the past, a tubular textile jacket which is normally a fabric havingbeen woven with warps and a weft in a tubular form was coated on theexternal surface thereof with a latex of natural rubber or a syntheticresin and then turned inside out in the open air to manufacture a firehose. In a typical method for manufacturing such fire hose comprised aseries of continuous steps of dipping a tubular textile jacket reeledoff from a supply reel into a bath of an emulsion of a latex or asynthetic resin, drying the tubular textile jacket while being kept inan inflated state to form a coating of a latex of natural rubber of asynthetic resin on the external surface of the jacket and thereafterturning the tubular textile jacket inside out in the open air byapplying a pressurized fluid to the interior space of the jacket to forma fire hose having a resinous coating on the inner surface thereof. Themost advantageous method of this type, for example, a method disclosedin U.S. Pat. No. 4,020,790 is still utilized for the manufacture of firehose.

In recent years, such tubular textile jacket with a coating of asynthetic resin on the external surface thereof has been utilized as alining material for pipe lines, especially underground pipe lines suchas gas conduits, city water pipe lines, petroleum pipe lines, sewagepipes made of concrete or porcelain and pipe lines enclosing powertransmission wires or telecommunication cables. In case of suchunderground pipe lines, their superannuation or damage often causesdangerous leakage of combustible fluids or electricity and unexpectedburst of water, thus resulting in accidents and traffic disturbance.Only one effective countermeasure taken in the past to prevent suchtroubles was to dig up the superannuated or damaged pipe lines over thelength in the order of several ten or hundred meters for replacing themwith new ones. During this pipe-exchange work, people encounters muchtrouble since supply of gas or city water or fuels is discontinued andeven traffic is limited where the pipe lines are buried below the publicroads. In this case, much labor and cost are required for thepipe-exchange work in addition to the difficulty in the work itself.Thus, development of such pipe-lining material and a method for applyingit to underground pipe lines attracts commercial interest because thereis no longer necessity of digging up the pipe lines already constructed.A method for lining pipe lines with such resin-coated tubular textilejacket as a tubular lining material has been improved hitherto severaltimes and a typical one now advantageously utilized is disclosed, forexample, in U.S. Pat. No. 4,334,943 and comprises passing such tubularlining material through a pipe line and evaginating it within the pipeline under fluid pressure while bonding the evaginated tubular liningmaterial onto the inner surface of the pipe line by the aid of a binderwith or without using a leading rope-like material which has previouslybeen passed through the tubular lining material beyond its full lengthand is drawn from the opposite end of the pipe line. It has been found,however, that the tubular textile jacket with a coating of a syntheticresin on the external surface thereof which can be manufacturedaccording to a method as disclosed in U.S. Pat. No. 4,020,790 is notsuitable as a tubular lining material for the above pipe-lining method.According to the method described in this patent, a tubular textilejacket is dipped in a bath of an emulsion of a latex or a syntheticresin whereby the emulsion is penetrated deeply into the interstices ofthe fabric structure and is solidified in the subsequent drying step toharden the textile jacket. It is difficult to evaginate the hardenedtubular textile jacket within a narrow space, i.e. a pipe line undernormal fluid pressure. If the fluid pressure is elevated to strengthenthe force necessary for evagination, the tubular lining material mayoften be damaged or stress may be formed therein under such highpressure.

With the improvements made in the pipe-lining methods, some improvementshave also been made in tubular lining materials themselves. Thus, atubular lining material used in the pipe-lining method described in U.S.Pat. No. 4,334,943 is a textile jacket woven in a tubular form withwarps and a weft made of polyester yarns and having on the externalsurface thereof a coating of a polyester resin. The synthetic resin usedin this tubular lining material is generally a thermoplastic polyesterelastic resin such as Pelprene (Toyobo, Japan) or Hytrel (DuPont,U.S.A.) while the binder is preferably a commercially availablethermocurable epoxy resin. As the polyester elastic resin possesses bothstrength and flexibility, this tubular lining material can provide astrong and satisfactory inner backing for the pipe lines. However, aproblem exists in this polyester resin with respect to cohesion to theepoxy binder and to the textile jacket made of polyester yarns.

In general, what is requested for the tubular lining material is that itmust be impregnated with a sufficient amount of a binder before thelining treatment but must easily be evaginated under a relatively weakfluid pressure so that the lining material can be bonded, afterevagination, strongly onto the inner surface of a pipe line to form anintegrally solidified reinforced textile pipe line within the pipe lineas if the reinforced textile jacket were regarded as a second pipe lineformed within the pipe line treated. In particular, the followingproperties are requested for the coating of a synthetic resin:

(1) To be flexible (The coating should be flexible for maintainingflexibility of the lining material. The hardness or the coating ispreferably soft enough to assure evagination of the tubular liningmaterial or less than 95 in terms of Shore A hardness.)

(2) To have a sufficient tensile strength

(3) To possess stretchability

(4) To be lower in frictional resistance between the coatings and to bebetter in anti-abrasion resistance

(5) To be excellent in the resisting properties against chemicals,solvents, water and fungi

(6) To be heat-resistant

(7) Not to degrade against a binder to be used

(8) To show good cohesion between the coating and the binder aftercuring of the binder

(9) To be easily moldable (As an extrusion molding method is usuallyutilized to form a coating of a synthetic resin on the external surfaceof the tubular textile jacket, the synthetic resin is required to havegood moldability.)

(10) To show good adhesion to the tubular textile jacket by extrusionmolding.

As the thermoplastic polyester elastic resin cannot be applied onto theexternal surface of a tubular textile jacket according to the so-calleddipping method wherein the jacket is dipped in a bath of an emulsion orsolution of the resin and then dried, tubular lining materials employedin the current pipe-lining methods as disclosed in U.S. Pat. Nos.4,334,943, 4,368,091, 4,350,548 and 4,427,480 are manufactured byapplying the elastic resin onto the tubular textile jacket according toan extrusion molding method wherein the resin is extruded while hot ontothe external surface of the tubular textile jacket in inflated state.The thermoplastic polyester elastic resin such as Pelprene or Hytrelsubstantially satisfies the above requirements (1)-(7) and (9) and isgenerally preferably used as a coating on the tubular textile jacket.Improved adhesion of the polyester resin to the tubular textile jacketmay be achieved in the following manner: when the resin is extrudedunder high pressure onto the surface of the textile jacket on extrusionmolding, the resin is forced to penetrate deeply into the interstices ofthe fabric structure of the textile jacket whereby the resin is stronglybonded to the textile jacket by a so-called anchoring action. However,this device bears on the other hand such a disadvantage that the resindeeply intruded into the textile jacket is solidified to damageflexibility of the lining material and gives no sufficient space in thejacket for absorbing a necessary amount of a binder. The tubular liningmaterial having poor flexibility cannot easily be evaginated within apipe line unless the fluid pressure be elevated, and cannot be bondedfirmly onto the inner surface of the pipe line when impregnated with aninsufficient amount of the binder. At present, a new type syntheticresin of excellent coating characteristics has not yet been developedwhich can be substituted for the thermoplastic polyester elastic resinnow suitably used as a resinous coating on the tubular textile jacketmade of polyester yarns.

Under these circumstances, there is a technical subject for improvingadhesion of the thermoplastic polyester elastic resin to the textilejacket and also a great demand for developing a new tubular liningmaterial having on the external surface thereof a coating of a syntheticresin which satisfies all of the above requirements (1)-(10) and canstrongly be bonded to the textile jacket without any sacrifice of itsflexibility and complete adhesion of the lining material to the innersurface of the pipe line.

BRIEF SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide atubular lining material which overcomes the above mentioneddisadvantages which is provided on the external surface thereof with acoating of a combination of the suitably selected synthetic resins inlayers superficially but strongly bonded to the textile jacket of thelining material.

It is another object of the present invention to provide a method ofmanufacturing a tubular lining material with a coating of a combinationof the suitably selected synthetic resins in layers superficially butstrongly bonded onto the external surface thereof by a specificsimultaneous multiple extrusion molding technique.

It is still another object of the present invention to provide anapparatus for manufacturing a tubular lining material with a coating ofa combination of the suitably selected synthetic resins in layerssuperficially but strongly bonded onto the external surface thereofwhich comprises a specifically designed multiple extruder.

Other objects, features and advantages of the present invention willbecome apparent more fully from the following description.

DETAILED DESCRIPTION OF THE INVENTION

As a result of the present inventors' study for developing a tubularlining material which overcomes all the drawbacks seen in the prior arttubular lining materials, it has now been found surprisingly that suchdrawbacks can entirely be overcome by applying a coating of acombination of the suitably selected synthetic resins in layers, e.g. acoating of a synthetic resin composed predominantly of a thermoplasticpolyester elastic resin as the outer layer and a synthetic resincomposed predominantly of a thermoplastic polyurethane elastic resin asthe inner layer in place of a coating of the thermoplastic polyesterelastic resin alone, onto the external surface of the tubular textilejacket according to a specific simultaneous extrusion molding techniqueto form a tubular lining material provided on the external surfacethereof with a coating of a combination of the suitably selectedsynthetic resins in layers.

In accordance with one embodiment of the present invention, there isprovided a tubular lining material for pipe lines which comprises atubular textile jacket having on the external surface thereof a coatingof plural synthetic resins in the form of laminated layers,characterized in that the outermost layer of the coating is composedpredominantly of a thermoplastic polyester elastic resin and theinnermost layer of the coating is composed predominantly of athermoplastic polyurethane elastic resin, the coating having been bondedsuperficially onto the external surface of the tubular textile jacket.

In accordance with another embodiment of the present invention, there isprovided a method for manufacturing a tubular lining material for pipelines which comprises pulling a tubular textile jacket downwardly at aconstant speed through an annular extrusion head having multipleextruders with downwardly opened nozzles at the front end thereof eachin an annular shape capable of extruding plural thermoplastic syntheticresins simultaneously around the external surface of the descendingtubular textile jacket inflated at the front end of the extrusion headsto a cylindrical form by way of a mandrel chip having an outer diametersubstantially equal to or slightly smaller than the inner diameter ofthe tubular textile jacket and being mounted to a hollow evacuationshaft having been inserted thereinto, downwardly extruding the pluralthermoplastic synthetic resins simultaneously in the form of laminatedlayers from the nozzles evenly onto the external surface of the tubulartextile jacket, evacuating the interior of the tubular textile jacket ina portion downstream of the mandrel chip through the hollow evacuationshaft while maintaining the tubular textile jacket in inflated formthereby holding the synthetic resins in the form of laminated layerssuperficially on the external surface of the tubular textile jacket, andthereafter allowing the synthetic resins to be solidified by passing thetubular textile jacket through a cooling medium.

In accordance with still another embodiment of the present invention,there is provided an apparatus for manufacturing a tubular liningmaterial for pipe lines which comprises a means for pulling a tubulartextile jacket downwardly at a constant speed, an annular extrusion headhaving multiple extruders each with a downwardly opened annular nozzleat the front end thereof arranged in an annularly layered form capableof extruding plural synthetic resins in the form of laminated layers onthe external surface of the tubular textile jacket, a mandrel located onthe central axis of the apparatus and spaced from the annular nozzleswhich has an outer diameter substantially equal to or slightly smallerthan the inner diameter of the tubular textile jacket, a means forevacuating the interior of the tubular textile jacket in a portiondownstream of the mandrel tip and having a device located in thedownstream portion of the tubular textile jacket for maintaining it ininflated form, and a means for solidifying the synthetic resins in theform of laminated layers coated on the tubular textile jacket.

It has been found that a thermoplastic polyurethane elastic resin hasgood compatibility with the thermoplastic polyester elastic resin andshows good adhesion to the tubular textile jacket especially knitted orwoven in a tubular form with warps and weft each made of polyester yarnsand also to an epoxy type binder. Thus, the adhesion of thethermoplastic polyester resin to the tubular textile jacket and to thebinder is markedly improved by interposing a thermoplastic polyurethaneelastic resin between the thermoplastic polyester elastic resin and thetubular textile jacket. The tubular lining material of the presentinvention is therefore characterized by having on the external surfacethereof a coating of plural synthetic resins in the form of laminatedlayers, the outermost layer being composed predominantly of thethermoplastic polyester elastic resin and the innermost layer beingcomposed predominantly of the thermoplastic polyurethane elastic resin.In the simplest case, the resinous coating consists of two layers, theouter layer being composed exclusively or predominantly of thethermoplastic polyester elastic resin and the inner layer being composedexclusively or predominantly of the thermoplastic polyurethane elasticresin. For further improving mutual adhesion between such outer layerand such inner layer, a small proportion of the thermoplasticpolyurethane elastic resin can be incorporated into the outer layerwhile a small proportion of the thermoplastic polyester elastic resinmay be incorporated into the inner layer. If necessary, one or moreintermediate layer composed of the thermoplastic polyester elastic resinand the thermoplastic polyurethane elastic resin in various proportionsmay be interposed between the outer layer composed exclusively orpredominantly of the thermoplastic polyester elastic resin and the innerlayer composed exclusively or predominantly of the thermoplasticpolyurethane elastic resin.

The present invention can more fully be understood from the followingdescription taken in conjunction with the accompanying drawings inwhich:

FIG. 1 is a schematic partially broken perspective view of one exampleof the tubular lining material of the present invention having twolaminated layers of synthetic resins on the external surface thereof.

FIG. 2 is a schematic section view of the tubular lining material shownin FIG. 1 cut along theline α-β.

FIG. 3 is a schematic elevation of an example of the apparatus of thepresent invention for manufacturing the tubular lining material as shownin FIG. 1.

FIG. 4 is a schematic section view of a conventional extruder.

FIG. 5 is a schematic section view of an example of the extruderinvolved in the apparatus of the present invention as shown in FIG. 3.

FIG. 6 is a schematic fragmentary longitudinal section view showing thestate of adhesion of the synthetic resin to the tubular textile jacketin case of using a conventional extruder as shown in FIG. 4.

FIG. 7 is a similar view to FIG. 6 but showing the state of adhesion ofthe synthetic resins to the tubular textile jacket in case of using theextruder involved in the apparatus of the present invention.

FIG. 8 is a similar view to FIG. 6 but showing the state of adhesion ofthe synthetic resins to the tubular textile jacket in case of anotherextruder involved in the apparatus of the present invention.

Referring first to FIG. 1, a tubular textile jacket A woven in a tubularform with warps a and a weft b has on the external surface thereof aresinous coating B which is composed of an outer layer 12 and an innerlayer 11 each composed of a different synthetic resin. In general, thewarps and the weft are respectively made of polyester yarns possessingflexibility and strong tenacity. In principle, the outer resinous layeris composed exclusively or predominantly of a thermoplastic polyesterelastic resin and the inner resinous layer is composed exclusively orpredominantly of a thermoplastic polyurethane elastic resin forattaining strong adhesion of the resinous layers to the tubular textilejacket.

In FIG. 2 showing the cross section of the tubular lining material shownin FIG. 1 cut along the line α-β, the tubular textile jacket A isusually manufactured by weaving warps and a weft each made of syntheticyarns in a tubular form. Used as the warps are generally polyestermultifilament yarns or crimped yarns. Used as the weft is generally aspun yarn made of polyester, polyamide or a blend of such syntheticfibers. Twisted yarns of polyester multifilament yarns or crimped yarnsand polyester spun yarns are also preferably used as the weft. The useof polyester yarns is preferable since they are resistant to heat andchemicals and possess high tenacity. The tubular textile jacket has onthe external surface thereof a resinous coating composed of at least twolayers of synthetic resins. The thickness of the resinous coating Bvaries according to the intended purpose and size or inner diameter ofthe pipe lines to be treated, but is usually within the range from about0.2 mm to about 0.8 mm, preferably from 0.3 mm to 0.6 mm. In FIG. 2showing the case of the coating B composed of the two layers 11 and 12,the ratio in thickness of the outer layer 12 to the inner layer 11 isusually withing 1:1 to 2:1. In case the coating is composed of three ormore layers, the ratio in thickness of these layers may be equal but theoutermost layer composed usually of a thermoplastic polyester elasticresin is preferably thicker than the other layers. In general, the innerlayer/layers function as intermediate layer/layers for improvingadhesion of the outer layer to the tubular textile jacket and may thusbe thin so far as the desired improvement in the adhesion be achievedthereby.

A thermoplastic polyurethane elastic resin is preferably used as theinner resinous layer, which is derived from a diisocyanate and a polyoland glycol. Illustrative of the diisocyanate is, for example,4,4'-diphenylmethanediisocyanate, 4,4'-dicyclohexylmethanediisocyanateand hexamethylene diisocyanate. On the other hand, examples of thepolyol include polyethylene adipate, poly(1,4-butylene) adipate,polycaprolactone and polytetramethylene glycol and examples of theglycol include ethylene glycol, 1,4-butanediol, 1,6-hexanediol andbishydroxyethoxybenzene. A thermoplastic polyurethane elastic resin of apolyether type derived from a combination of 4,4'-diphenylenediisocyanate, polytetramethylene glycol and 1,4-butanediol isparticularly suitable because of its excellent anti-fungi property andhydrolysis-resisting property.

It has been found that the use of a thermoplastic polyurethane elasticresin of an incomplete thermoplastic type, i.e. one having a molar ratioin the NCO ingredient/the OH ingredient (or R value which is a ratio of--NCO/--OH) of 1.05-1.3, is preferable for the present invention. Apolyurethane resin of such incomplete thermoplastic type has -NCO groupsin the terminal ends of the molecue and forms crosslinked bridges by thereaction between the urethane bonds and unreacted isocyanate groupscaused by the action of heat or water. Thus, adhesion to the tubulartextile jacket and peeling strength are enhanced. Various polyurethaneresins of such incomplete thermoplastic type are commercially availablefrom Nihon Elastoran Co., Japan under the trade name of Elastoran (e.g.Elastoran E 375). As this polyurethane resin is so strong in adhestionto the tubular textile jacket, it attains the desired effect even incase of being applied superficially onto the textile jacket.

A thermoplastic polyester elastic resin used as the resin constitutingthe outer layer is a block copolymer containing an aromatic polyester asa hard segment thereof and either or both of an aliphatic polyether andaliphatic polyester as a soft segment thereof.

The aromatic polyester used as the hard segment is a polycondensate ofan acid and a glycol. Examples of the acid include aromatic dicarboxylicacids such as terephthalic acid, isophthalic acid, orthophthalic acidand naphthalenedicarboxylic acid. Examples of the glycol includealiphatic or cycloaliphatic glycols with 2-12 carbon atoms such asethylene glycol, 1,3-propanediol, 1,4-butanediol and 1,6-hexanediol.

The aliphatic polyether used as the soft segment is preferably a polymerof an alkylene oxide with 2-10 carbon atoms, which has an averagemolecular weight of 400-6000. Illustrative of such polymer is, forexample, block polymers or random copolymers of ethylene glycol andpropylene glycol, polyethylene glycol, polypropylene glycol,polytetramethylene glycol and hexamethylene glycol. These polymers canbe used singly or as a mixture. The aliphatic polyester used as thesoftsegment is a polyester such as polyethylene adipate, polytetramethylenesebacate of a polyester of a dimeric acid and an alkylene glycol, andalso includes aliphatic copolymeric polyesters derived from acidmixtures and glycol mixtures. These polyesters can be used singly or asa mixture. A polylactone such as poly(epsiloncaprolactone),polyvalerolactone or the like may also be used.

Among these thermoplastic polyester elastic resins, a blockcopolyester-polyether derived from terephthalic acid, 1,4-butanediol andpolytetramethylene glycol and containing 80% by weight of the polyethercomponent is preferable and has a 50% modulas of 25 Kg/cm, a tensilestrength of 180 Kg/cm and an elongation on breaking of 800% whenmeasured according to the testing method of JIS K-6301. The use of athermoplastic polyester elastic resin containing a polyester derivedfrom terephthalic acid or naphthalenedicarboxylic acid and1,4-butanediol as a hard segment thereof and polytetramethylene glycolas a soft segment thereof is most preferable in the present invention.Such resins are commercially available from Toyobo Co., Japan under thetrade name of Pelprene (e.g. Pelprene 150M and Pelprene P40B or P40H).These resins are also excellent in moldability on extrusion,hydrolysis-resisting property, water-resistance and anti-fungi property.If desired, liquid paraffin, wax or graphite may be added to thesethermoplastic polyester elastic resins to minimize their frictionalresistance. In this case, the amount of such additive may not influencethe characteristic properties of the polyester resins.

As described hereinbefore, the thermoplastic polyester elastic resinusually constituting the outer layer may be incorporated with a smallproportion of the thermoplastic polyurethane elastic resin while thethermoplastic polyurethane elastic resin usually constituting the innerlayer may be incorporated with a small proportion of the thermoplasticpolyester elastic resin, thereby improving the compatibility of theseresins and the adhesion of the thermoplastic polyester elastic resin tothe textile jacket. In a preferable embodiment, the resinous coating canbe composed of the three layers; the outermost layer composedexclusively or predominantly of the thermoplastic polyester elasticresin, the intermediate layer composed of an equiproportion of thethermoplastic polyester elastic resin and the thermoplastic polyurethaneelastic resin and the innermost layer composed exclusively orpredominantly of the thermoplastic polyurethane elastic resin. In suchmulti-layer structure, adhesion of the resinous coating to the tubulartextile jacket is satisfactorily improved and no delamination occurs. Ithas been found that the tubular lining material of such double or triplelayer structure is found to satisfy all of the requirements for thelining materials and is excellent in flexibility as compared with theconventional prior art tubular lining materials. This is ascribable tothe fact that the tubular lining material of the present inventioncontains a thermoplastic polyurethane elastic resin which is almostequivalent in hardness but has a low modulas on weak stretching ascompared with the thermoplastic polyester elastic resin. Thethermoplastic polyurethane elastic resin also shows good adhesion to anepoxy type binder, probably due to the fact that the polyurethane resinhaving an R value of 1.05-1.3 is reactive to the amine ingredient of theepoxy type binder. Thus, the tubular lining material of the presentinvention can easily be evaginated within a pipe line because of itsexcellent flexibility and does not permit the formation of any pinholein the resinous coating.

Such technical advantage results apparently from the selection of acombination of specific synthetic resins as a resinous coating and froma specific structure of the laminated coating on the textile jacket.This specific structure is formed by a unique resin-extrusion techniquewherein a viscous laminar flow of the thermoplastic polyester andpolyurethane elastic resins is superficially attached onto the externalsurface of the tubular textile jacket. As the resins are not penetrateddeeply into the interstices of the fabric structure, the tubular textilejacket fully retains its good flexibility. In addition, the resinouscoating is strongly bound with the textile jacket and with the bindereven if the resinous coating is superficially applied onto the externalsurface of the tubular textile jacket because of excellent adhesionbrought about by the thermoplastic polyurethane elastic resin used inthe inner layer of the resinous coating.

The synthetic resins above mentioned may be incorporated with a smallamount of other polymers, antioxidants, modifiers, fillers, colorantsand the like additives known in this art so far as the incorporation ofsuch additive does not affect the characteristics of the syntheticresins.

The tubular lining material having on the external surface thereof acoating of plural synthetic resins in the form of laminated layers canbe manufactured according to the method using an apparatus as shown inFIG. 3.

In FIG. 3 showing an example of the apparatus of the present inventionfor manufacturing a tubular lining material having on the externalsurface thereof a coating of two synthetic resins in the form oflaminated layers, the essential part of which is shown in section in anenlarged scale, an extrusion device 1 for a thermoplastic polyurethaneelastic resin for forming an inner layer and an extrusion device 2 for athermoplastic polyester elastic resin for forming an outer layer has acommon extrusion head 3 which is vertically positioned and connected tothe devices 1 and 2. The extrusion head 3 includes inner and outercylindrical members 4 and 5, the inner cylindrical member 4 beingprovided at its center with an axially extending cavity 6 a lower end ofwhich has a reduced diameter equal to or slightly larger than the outerdiameter of a tubular textile jacket 7, an axially extending annularpassage 8 defined by the inner and outer members 4 and 5, the passage 8being communicated as its upper end with the extrusion device 1, anotherannular passage 9 cocentrically extending in the outer member 5, and thepassage 9 being also communicated at its upper end with the extrusiondevice 2. There is further defined an annular extrusion nozzle 10between the lower ends of the inner and outer members 4 and 5, theannular nozzle 10 being radially spaced away with a slight distance fromthe reduced lower end of the cavity 6 and communicated with the passages8 and 9, the arrangement being such that the thermoplastic polyurethaneelastic resin 11 and the thermoplastic polyester elastic resin 12 aresimultaneously extruded from the devices 1 and 2 into the passages 8 and9, respectively, when extrusion screws 1' and 2' are operated at thesame time, and are then discharged from the nozzle 10 as a laminar flowonto the external surface of the tubular textile jacket 7 downwardlypassing through the lower end of the cavity 6 whereby a coating of thethermoplastic polyurethane elastic resin 11 and the thermoplasticpolyester elastic resin 12 in the form of laminated layer is formed onthe external surface of the tubular textile jacket 7.

In the lower end portion of the cavity 6 is located a cylindricalmandrel chip 13 having an outer diameter substantially equal to orslightly smaller than the inner diameter of the tubular textile jacket7. The mandrel chip 13 is provided at its lower end with an O-ring 14sealingly engaged with the tubular textile jacket 7. Extendingvertically through the mandrel chip 13 is a hollow shaft 15 which ispositioned at its upper end in an evacuation device 16 sealingly mountedonto the extrusion head 3. The upper end of the shaft 15 is formed witha radial hole 17 through which the inner axial space of the shaft 15 iscommunicated with an inner space 18 of the evacuation device 16 andfurther through a port 19 with a suitable vacuum pump (not shown). Thespace 18 of the device 16 is defined by a pair of axially spaced sealingdiscs 20 and 21 which are laterally mounted onto the shaft 15, each ofthe sealing discs being provided at its outer periphery with an O-ring22 sealingly engaged with the textile jacket 7. It should be noted thata portion A of the textile jacket 7 descending in the device 16 and thehead 3 is not yet coated with the resins so that a gaseous fluid or aircan freely flow through apertures formed in the fabric structure of thetextile jacket 7.

A lower end of the shaft 15 is downwardly extended beyond the mandrelchip 13 and formed with a plurality of axially spaced radial holes 24.The shaft 15 is also provided there with a plurality of axially spaceddiscs 25 for defining spaces 26 within a portion B of the tubulartextile jacket 7 of which the outer surface has just been coated withlaminated layers of the thermoplastic synthetic resins 11 and 12. Thediscs 25 have an outer diameter substantially equal to that of themandrel chip 13. Each space 26 is evacuated through the correspondinghole 24, the inner space of the shaft 15, the hole 17 and the port 19. Arod 27 extends upwardly from the upper end of the hollow shaft 15 and isprovided at its upper end with a holder 28 in a bullet form. A pair ofrollers 29 is rotatably mounted on a shoulder portion of the holder 28and supported externally by a pair of rollers 30. July below the rollers30, there is provided a pair of feed rollers 31 for feeding the tubulartextile jacket 7 downwardly at a constant speed. The holder 28 alsoserves to inflate the tubular textile jacket 7 fed in inflated state.Usually, a preheating device 32 is provided between the rollers 31 andthe evacuation device 16 for preheating the jacket 7 passingtherethrough with hot air entering from a port 33 and going out from aport 33'. Also provided downstream of the lower end of the shaft 15 is awater bath 34 for cooling the jacket 7 coated with the laminated layersof the synthetic resins. In the bath 34 a roller 36 is positioned sothat the jacket 7 passes about the roller 36 and moves out of the bath34 through water 35 as an inert cooling medium. In place of the waterbath 34, a cooling chamber (not shown) may be positioned where thejacket 7 is passed in counterflow with a stream of a cooling air orinert gas to accelerate solidification of the synthetic resins coated onthe jacket. A tubular lining material thus manufactured is conveyedthrough a guide roller 37 and a belt conveying device 38 and wound on ashaft 39 of a take-up reel 40.

On the other hand, the tubular textile jacket 7 is supplied in aflattened state from a take-off reel 41 of a supply coil 42 through aguide roller 43 and inflated in a cylindrical form by the holder 28 in abullet form and fed by the action of a pair of the feed rollers 31 alongthe rod 27 passing through the preheating device 32. The jacket isfurther inflated to circular in cross section by the sealing discs 20and 21. In the subsequent coating process, the jacket 7 is maintained incompletely inflated state by the mandrel chip 13 and the discs 25against the evacuation by the evacuation device 16 so that thethermoplastic synthetic resins are applied evenly onto the externalsurface of the tubular textile jacket 7.

In FIG. 4 showing an enlarged fragmentary section of a conventinoalextrusion device 101 for a single synthetic resin, a lower part of anannular extrusion nozzle 105 is projected to form a projected portion105' positioned closely to the tubular textile jacket in a portion A sothat a thermoplastic resin 109 discharged from the nozzle is squeezedbetween the external surface of the jacket in the portion B and theprojected portion 105' whereby a part of the synthetic resin is allowedto penetrate into interstices formed in the fabric structure of thetextile jacket 7. The remaining part of the synthetic resin is appliedonto the external surface of the jacket and form a coating on the jacketin a portion C. The shaft 100 may have a hollow structure and in thiscase it may extend downwardly beyond the mandrel chip to evacuate theinterior of the jacket 7 in the portion C. An O-ring 114 functions as asealing member when the evacuation is applied. A notch is formed in anupper part 104 of the nozzle so that a relatively large amount of thesynthetic resin is discharged from the nozzle and squeezed between thedescending jacket and the projected portion 105'.

In FIG. 5 showing an enlarged fragmentary section of an extrusion deviceof the present invention which can extrude two synthetic resins 11 and12 at the same time through the passages 8 and 9, respectively, an innercylindrical member 4 is extended and oriented downwardly so that thesynthetic resins 11 and 12 discharged from the annular nozzle 10 descendas a laminar flow parallelly with the descending jacket inflated in aportion A by the mandrel chip 13. Thus, the jacket is not yet broughtinto contact with the laminar flow of the synthetic resins in a portionB. The jacket in a portion C confined from the portion B by the O-ring14 is evacuated through the hollow evacuation shaft 15 extendingdownwardly through the mandrel chip 13 whereby the laminar flow of thesynthetic resins is allowed to contact superficially with the externalsurface of the tubular textile jacket.

FIGS. 6, 7 and 8 are schematic enlarged fragmentary longitudinal sectionviews showing the state of adhesion of the synthetic resin to theexternal surface of the tubular textile jacket, among which FIG. 6 showsthat case obtained by using a conventional extruder.

In FIG. 6, the tubular textile jacket A woven with the warps a and theweft b is impregnated fully with the synthetic resin in such manner thatthe resin 6 is forced to penetrate deeply into the interstices of thefabric structure of the textile jacket, as shown by the dotted lines.Thus, the resultant tubular lining material becomes poor in flexibilityand is hardly evaginated within a pipe line unless a higher fluidpressure be applied. The use of such a high pressure often damages thequality of the lining material. In addition, the space for absorbing abinder becomes smaller, thus resulting in such a drawback that theadhesion of the lining material onto the inner surface of a pipe linebecomes inferior to cause peeling of the lining material. As shown inFIG. 6, the thickness of the resin reaches a half of the total thicknessof the resin-coated tubular textile jacket C.

In FIG. 7 showing the case of applying two layers of the syntheticresins onto the external surface of the tubular textile jacket whereinA, C, a and b have the same meaning as given in FIG. 6, a resinouscoating B composed of an inner layer of the thermoplastic polyurethaneelastic resin 11 and an outer layer of the thermoplastic polyesterelastic resin 12. As the resins 11 and 12 are extruded simultaneously asa laminar flow by the extruder as shown in FIG. 5, the coating B issuperficially attached to the external surface of the jacket A. Becauseof good adhesion of the resin 11 to the jacket A and to the resin 12,however, the coating B is strongly bound with the jacket A withoutdamaging flexibility of the jacket A.

In FIG. 8 showing the case of applying three layers of the syntheticresins onto the external surface of the tubular textile jacket whereinA, B, C, a, b, 11 and 12 have the same meanings as given in FIG. 7, anintermediate layer 44 composed of an equiproportion of the resin 11 andthe resin 12, and the thickness of the coating B is somewhat enlarged toshow the triple layer structure, the layers are formed in a similarmanner to that in FIG. 7 by using a triple extruder similar to thedouble extruder as shown in FIG. 5. In this case, the coating B issuperficially attached to the external surface of the jacket A withoutdamaging flexibility of the jacket A. Adhesion of the coating is muchmore improved in this example.

In the apparatus of the present invention, the viscous thermoplasticresins 11 and 12 extruded onto the external surface of the jacket 7still have a high temperature sufficient to be plastically movable.Since the spaces 26 are evacuated by the evacuation device 16, theresins are attached superficially onto the surface of the jacket 7 butare not penetrate into the jacket 7 because of their high viscosity toform a coating superficially on the jacket. The length of the evacuationshaft 15 downstream of the mandrel chip 13 is thus suitably controlledaccording to the viscosity, temperature and other conditions. It ispreferable that the conveying speed of the jacket 7 by the beltconveying device 38 is substantially equal to or slightly higher thanthe feeding speed of the jacket by the feed rollers 31. If the conveyingspeed is too high, the frictional resistance between the portion B ofthe jacket 7 and the mandrel chip 13 and the discs 25 will be increased.On the other hand, if the conveying speed is too low, the portion A ofthe jacket 7 will be sagged to provide uneven thickness of the coatinglayer. The feed rollers 31 may be eliminated and the jacket 7 can bepulled only by the belt conveying device 38.

In preferable examples of the tubular lining material for reinforcing apipe line having a nominal diameter of 150 mm, a tubular textile jacketwas made of 444 warps, each comprised of three 1000 denier polyethyleneterephthalate multi-filament yarns and a weft made by twisting a 1100denier polyethylene terephthalate spun yarn and picked up at 62 pickcount/10 cm. The tubular textile jacket thus manufactured was used inthe following three examples and a comparative example.

In one example, the following coating was applied onto the tubulartextile jacket, using the apparatus as shown in FIG. 1:

The outer layer: a thermoplastic polyester elastic resin (Pelprene 150Mavailable from Toyobo Co., Japan)

The inner layer: a thermoplastic polyurethane elastic resin of polyethertype (Elastoran E375 available from Nihon Elastoran, Japan)

Thickness of the coating: 0.4 mm in average (the outer layer/the innerlayer=1/1).

In another example, the following coating was applied onto the tubulartextile jacket in a similar manner:

The outer layer: a thermoplastic polyester elastic resin plus athermoplastic polyurethane elastic resin (the same resins as those usedin the above; a blend ratio=4/1)

The inner layer: a thermoplastic polyurethane elastic resin plus athermoplastic polyester elastic resin (the same resins as those used inthe above; a blend ratio=4/1)

Thickness of the coating: 0.4 mm in average (the outer layer/the innerlayer=1/1).

In still another example, the following coating was applied onto thetubular textile jacket in a similar manner using an extruder for threeresins:

The outer layer: a thermoplastic polyester elastic resin (the same resinas that used in the above)

The intermediate layer: a thermoplastic polyester elastic resin plus athermoplastic polyurethane elastic resin(the same resins as those usedin the above; a blend ratio=1/1)

The inner layer: a thermoplastic polyurethane elastic resin (the sameresin as that used in the above)

The thickness of the coating: 0.4 mm in average (the outer layer/theintermediate layer/the inner layer=2/1/1).

In a comparative example, the following coating was applied onto thetubular textile jacket, using the extruder as shown in FIG. 4:

The coating: a thermoplastic polyester elastic resin (the same resin asused in the above)

The thickness of the coating: 0.4 mm in average.

In an actual pipe lining treatment for the pipe line of 150 mm in anominal diameter according to the method as disclosed in U.S. Pat. No.4,334,943, the following results were obtained which are shown in thefollowing table:

                  TABLE                                                           ______________________________________                                        Example       1       2       3     Comparative                               ______________________________________                                        Coating       two     two     three one                                                     layers  layers  layers                                                                              layer                                     Peeling strength                                                                            3-4     2-3     3-4   1-2                                       between the coating                                                           and the jacket                                                                (Kg/cm w)                                                                     Peeling strength after                                                                      8       4-5     8     1-2                                       curing of the binder                                                          (Kg/cm w)**                                                                   Flexibility (Pressure                                                                       0.4     0.45    0.4   0.8                                       for evagination)*1                                                            (Kg/cm.sup.2)                                                                 Delamination of                                                                             occur   none    none  --                                        the coating*2                                                                 ______________________________________                                         *1 An air pressure of compressed air necessary for causing evagination of     the tubular lining material within the pipe line of 150 mm in diameter        *2 A crumpling test after soaking in 20% benzene80% methanol for 24 hours     **An epoxy type binder                                                   

As is evident from the above tests, the best result was obtained in thesample having the triple layer coating. The tubular lining material ofthe present invention were found preferable as they are excellent inflexibility and peeling strength.

As many apparently widely different embodiments of the present inventionmay be made without departing from the spirit and scope thereof, it isto be construed that the present invention is not limited to thespecific embodiments thereof except as defined in the appended claims.

What is claimed is:
 1. A pipe provided with a tubular lining materialwhich comprises a tubular textile jacket having on the external surfacethereof a coating of plural synthetic resins in the form of laminatedlayers, characterized in that the outermost layer of the coating iscomposed exclusively or predominantly of a thermoplastic polyesterelastic resin and the innermost layer of the coating is composedexclusively or predominantly of a thermoplastic polyurethane elasticresin, the coating having been bonded superficially onto the externalsurface of the tubular textile jacket.
 2. The pipe according to claim 1,wherein the coating is composed of two layers of synthetic resins, theouter layer being composed exclusively or predominantly of athermoplastic polyester elastic resin and the inner layer being composedexclusively or predominantly of a thermoplastic polyurethane elasticresin.
 3. The pipe according to claim 1, wherein the coating is composedof three layers of synthetic resins, the outer layer being composedexclusively or predominantly of a thermoplastic polyester elastic resin,the intermediate layer being composed of a thermoplastic polyesterelastic resin and a thermoplastic polyurethane elastic resin in anequiproportion and the inner layer being composed exclusively orpredominantly of a thermoplastic polyurethane elastic resin.
 4. The pipeaccording to claim 1, wherein the thermoplastic polyurethane elasticresin has an R value of 1.05-1.3.
 5. The pipe according to claim 1,wherein the tubular textile jacket having been woven with polyesteryarns.